General-purpose resins such as polypropylene and polyethylene are very inexpensive and can foe easily molded. Therefore, such general-purpose resins are widely used in various kinds of fields.
However, such general-purpose resins have a problem that heat resistance is low. Therefore, it is difficult to apply such general-purpose resins to electric and electronic parts or automotive parts required to have heat resistance.
Patent Document 1 discloses a method for crystallizing a polymer resin including: exposing a crystalline polymer resin in a molten state to a pressurized atmosphere of a gas having solubility in the polymer resin to dissolve the gas in the resin; and cooling the resin in the pressurized atmosphere of the gas to solidify the resin. According to this method, it is possible to provide a polymer material and a molded article which have an improved crystallinity and improved heat resistance.